The number of background checks represents a new record, up more than 20% from the previous September high set in 2012, when 1,459,363 background checks were conducted.

September is also the fifth month in a row to set a record for background checks. May, June, July, and August all saw record numbers.

The number of checks done in a particular month is generally seen as a proxy for how many guns were sold. This year alone over 15 million background checks have already gone through the NICS, which is more than were conducted in 2010 and every year prior (NICS began recording numbers of firearm related background checks in 1998).

The report warns that there is not a one-to-one correlation between background checks and firearm sales. There are multiple factors that could skew the numbers.

A single background check doesn’t represent the number of firearms that were purchased by an individual. According to CNN Money, only 5 states require a background check if you purchase a gun from a private individual at a gun show.

As for why sales are so high, Fortune reported in June that it could possibly be caused by Obama calling for stricter gun control laws. As Business Insider’s Sam Ro said, “gunmakers don’t benefit from tighter gun control. They benefit when there are talks of tighter gun control but those talks go nowhere.”